Plural of Locus
“Locus” forms the irregular plural “loci.” The pair applies across ordinary formal uses and specialist uses such as mathematics or genetics, while this guide stays focused on number and form rather than subject-matter instruction.
The plural of “locus” is “loci.”
Key details
Choose the right form
| Meaning / situation | Form / construction | Decision |
|---|---|---|
| one location/center | locus | Singular. |
| two or more | loci | Standard plural. |
| discipline-specific plural | loci | Same plural form. |
Quick tests
Plural-choice test
Are you referring to more than one locus?
If yes: Use “loci.”
If no: Use singular “locus.”
Caveat: The page explains grammar only; specialist definitions belong to their respective fields.
Examples
The study compares two loci on the chromosome.
“Loci” is the plural.
The city became a locus of debate.
One takes singular “locus.”
Several loci of activity emerged.
Multiple centers take “loci.”
Further guidance
Core difference
Use “locus” for one and “loci” for more than one.
Fast Test
If the sentence refers to several locations, centers, or discipline-specific loci, use the plural “loci.”
Usage Boundary
Do not use “locuses” as the standard plural in the reviewed authority.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- LOCUS | English meaning - Cambridge Dictionary (opens in a new tab)Cambridge University Press · Cambridge gives loci as the plural of locus.